This invention pertains to a clockspring connector for enclosing electrical conductor cables, the clockspring connector electrically connecting a rotatable electric device with a stationary electric device.
While the present invention may have multiple applications, the most prevalent is for use in automobiles. An increasing number of automobiles have airbag crash systems. An airbag is typically located on the steering wheel facing the driver. The airbag must be in continuous electrical connection with sensors in the car body. The sensors provide an electrical signal to the airbag crash assembly which instantly inflates the airbag in the event of a crash. Accordingly, there is a need for an electrical connection between the rotatable portion of the airbag assembly which is mounted to the steering wheel, and the remaining portion of the assembly which is in a stationary position in the car body. Electrical connections between rotatable and stationary parts are well known. Typically, an electrical brush rests upon a conductive ring, with one of the parts being rotatable to provide such rotatable electrical connection. However, there is a risk, particularly during the impact of an accident, of a transient failure of electrical connection with a brush and ring system which result in failure of the entire airbag system crash assembly.
Accordingly, a clockspring connector has previously been developed, comprising an outer housing, a rotor member and a multiple of intermediate housing members for enclosing and connecting the members; the housing and rotor member rotatably associated with one another at a plurality of bearing surfaces. A "clockspring" is located inside the interconnector. The clockspring of prior art devices includes a single flat conductor cable having its ends conductively attached to conductor wires which pass out of the interconnector to unite the airbag to the sensing device. For example, U.S. Pat. No. 5,061,195 discloses a clockspring housing and assembly having a single flat conductor cable therein.
It has also been known in the art to reduce the length of the flat conductor cable in order to reduce cost and needed space within the clockspring housing. For example, U.S. Pat. No. 5,277,604 incorporates an assembly of at least eight rollers and turned-back portions of the flat conductor cable within the clockspring housing to decrease the length of the flat cable and also prevent buckling and enhance reliability and smooth rotation of the clockspring connector. Such a design requires a complex and expensive system of mounting the rollers. Such a design may be expensive and, as well, only accommodates a single flat conductor cable.
The use of a pair of conductor cables was disclosed in U.S. Pat. No. 3,763,455. The conductor cables were carried by an assembly of twenty spacers or rollers. This design also requires a multiplicity of parts, including numerous rollers which add to the assembly time and costs of the device.
As more controls are mounted on the steering wheel, more conductors are required to pass multiple electrical signals through the clockspring connector. Prior art clocksprings have included conductor cables having up to six conductors in each flat cable. The excess of six conductors is limited by the limited width of the flat conductor cable and the processing methods of manufacturing the flat cable. Accordingly, there is needed a clockspring connector which can accommodate more than six conductors.
It is another object of the present invention to provide a clockspring connector having a minimal amount of moving parts.
It is a further object of the present invention to provide a clockspring connector having flat conductor cable of minimal length.
It is another object of the present invention to provide a clockspring having a freely and independently rotating carrier member.
It is a further object of the present invention to provide a clockspring connector that reduces vibration of the flat conductor cable by use of a compliant roller member.